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Factor Analysis of Tree Distribution Patterns in Oklahoma
Author(s) -
Schnell Gary D.,
Risser Paul G.,
Helsel John F.
Publication year - 1977
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1935086
Subject(s) - precipitation , environmental factor , distribution (mathematics) , ecology , environmental science , geography , physical geography , biology , mathematics , meteorology , mathematical analysis
Factor analysis was used to elucidate 5 general distribution patterns for 76 tree species and 19 environmental variables for Oklahoma. Tree distributons were based on presence—absence data for the 77 Oklahoma countries. The 5 general factors group together species that exhibit (I) eastern; (II) widespread and uniform; (III) southeastern; (IV) western; and (V) widespread but not uniform distribution patterns with the state. Fourteen of the selected environmental variables were significantly associated with 1 or more of these factors. As expected, the eastern distribution factor included soil types restricted to that part of the state. Several sol types were also involved in the second factor (widespread and uniform distribution), which also included 2 precipitation variables. Factor III was the most clear—cut of those delineated; species associated with it are restricted to southeastern Oklahoma. Temperature variables exerted a substantial influence on this factor, suggesting that the temperature regime found in the state (particularly duringthe winter) is responsible for the restricted distributions of the associated species. The western distributon pattern of factor IV had its highest loading with Western Plains soil types, as well as July precipitation and temperature. Factor IV species are found in the areas of the state that are the hotest and driest during the summer. The fifth factor, which shows a "patchwork" pattern, included a number of exotics and species cultivated by man. On most factors, soil types exhibited higher loadings than did precipitation or temperature variables, reflecting in part the fact tht the former were coded as 2—state variables, but also suggesing that soil characteristics may restrict distributions of some tree species. The predominant position of temperature variables on at least 1 factor (i.e., III) and the lack of such a strong relationship involving the precipitation variables implies that the effect of temperature on trees is relatively more direct and modified less than that of precipitation by other aspects of the environment. _kw Biogeography _kw distribution patterns